Foldable ovenware container and method of production

ABSTRACT

A foldable or collapsible ovenware container that maintains a rigid shape while in use and can be folded into a smaller size for storage. The ovenware container includes rigid top and bottom portions separated by a flexible middle portion. The flexible middle portion includes thick and thin wall sections. Pressure applied to the top portion causes the flexible middle portion to collapse in an orderly manner toward the bottom portion, with the middle portion folding at each of the thin wall sections to create a plurality of folds or pleats in the middle portion in the collapsed configuration.

FIELD OF THE INVENTION

The present invention relates to ovenware containers and particularly toan ovenware container that includes an elastomeric portion that enablesthe container to be folded or collapsed when not in use to enable easyand more efficient storage.

BACKGROUND OF THE INVENTION

Conventional ovenware containers are usually of rigid structure and aretypically constructed of metal, ceramics, or glass such as Pyrex®. Mostkitchens, commercial and residential, typically stock a large range oftypes and sizes of ovenware containers in order to be prepared for themyriad cooking tasks that are encountered.

Conventional ovenware containers, as a result of their rigidconstruction, typically occupy a significant amount of space in thekitchen. All kitchens, especially residential kitchens that aretypically limited in space, would benefit from ovenware containers thatoccupy less space when not in use.

Recently, non-rigid or soft ovenware containers have been introduced.The prior art soft ovenware containers are typically constructed of softsilicone rubber and are so soft, typically having a Shore A hardness ofapproximately 40, that they can be flexed or bent out of shape. Althoughsoft ovenware containers can be flexed or bent into a smaller size toconserve space, they have the disadvantage that they must be supportedby a rigid pan or similar object for stability when lifted ortransported from one area to another. Soft silicone is not practical forlarge ovenware containers having deep sides or including a large volumeas the soft sides lack rigidity and, when filled with a liquid orsemi-liquid food such as cake batter, can buckle or have the sidesdeflect and cause spillage of the contents.

What is needed therefore is ovenware container that maintains a rigidshape when in use, without the use of a supporting pan, and can befolded to a smaller size to conserve space during storage.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a collapsibleovenware container which maintains a rigid shape while in use and whichcan be folded into a smaller size for storage. The ovenware containerincludes rigid top and bottom portions separated by a flexible middleportion. The flexible middle portion includes thick and thin wallsections. Pressure applied to the top portion causes the flexible middleportion to collapse in an orderly manner toward the bottom portion, withthe middle portion folding at each of the thin wall sections to create aplurality of folds or pleats in the middle portion in the collapsedconfiguration.

OBJECTS AND ADVANTAGES

Several advantages are achieved with the ovenware container of thepresent invention, including:

-   -   (1) The foldable ovenware container of the present invention has        the advantage that it can be folded into a compact shape for        storage. This greatly reduces the need for storage space for the        ovenware container when it is not in use.    -   (2) The foldable ovenware container of the present invention        maintains its shape when placed in its unfolded state. This is a        big advantage over prior art soft ovenware containers.    -   (3) In its unfolded state, the ovenware container of the present        invention is capable of supporting unstable foods such as        liquids or batters without collapse caused by errant bumping or        jostling by a handler.    -   (4) Unlike soft ovenware containers, the foldable ovenware        container of the present invention does not need to be supported        by a separate pan or other rigid object when being moved from        one location to another.    -   (5) The foldable ovenware container of the present invention can        be used in high temperature environments such as conventional        ovens.    -   (6) An ovenware container constructed entirely of silicone        rubber according to the present invention can be used in        microwave ovens.

These and other objects and advantages of the present invention will bebetter understood by reading the following description along withreference to the drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an ovenware container according to the presentinvention.

FIG. 2 is a sectional view of the ovenware container taken along line2-2 of FIG. 1.

FIG. 3 is a side view of the ovenware container of FIG. 1 in a collapsedor folded state.

FIG. 4 is a sectional view of the ovenware container taken along line4-4 of FIG. 3.

FIG. 5 is a sectional view of a second embodiment of the ovenwarecontainer of the present invention.

FIG. 6 is a sectional view of a third embodiment of the ovenwarecontainer of the present invention.

FIG. 7 is a sectional view of a fourth embodiment of the ovenwarecontainer of the present invention.

FIG. 8 is a bottom view of the ovenware container depicted in FIG. 1.

TABLE OF NOMENCLATURE

The following is a listing of part numbers used in the drawings alongwith a brief description:

Part Number Description 20 ovenware container 22 bottom portion 24middle portion 26 top portion 28 thin wall section 30 thick wall section32 top edge 34 bottom edge 36 handle 37 bottom of container 38 extension39 pleat or fold 40 ovenware container, second embodiment 50 ovenwarecontainer, third embodiment 60 ovenware container, fourth embodiment

DETAILED DESCRIPTION

With reference to a first and preferred embodiment in FIG. 1, thepresent invention is an ovenware container 20 and a method of producingthe ovenware container. The ovenware container includes a bottom portion22, a middle portion 24 extending from the bottom portion 22, and a topportion 26 extending from the middle portion 24.

Referring to the cross-sectional view in FIG. 2, the middle portion 24of the ovenware container 20 includes one or more thin wall sections 28separated by thick wall sections 30. The thin wall sections 28 areplanar and arranged parallel with the bottom edge 34 of the container20. The thin wall sections 28 render the container foldable, with thecontainer 20 capable of folding at each of the thin wall sections 28.The container 20 further includes a top edge 32, a bottom edge 34, and ahandle 36 extending from the top portion 26. The container 20 canfurther include extensions 38 extending from the bottom edge 34. Asshown in FIG. 8, the extensions 38 extend from the bottom 37 of theovenware container 20 and provide a set-off for elevating the bottom 37of the container away from any surface it is placed upon. The extensions38, being out of direct contact with the bottom 37 of the container 40,provide a cooler lower contact surface when placing the container on asurface.

As shown in FIGS. 3 and 4, in which the ovenware container 20 is shownin a folded configuration, the vertical profile of the container 20 canbe reduced dramatically for storage purposes, allowing several ovenwarecontainers to be stacked on top of one another (not shown) and therebyreducing the amount of space required for storage. As shown in FIG. 4,the container 20 has folded at each of the thin wall sections 28. Aspressure is applied to the top edge 32 of the container 20 the containerfolds in sequence at each of the thin wall sections 28 until it isfolded at all of the thin wall sections 28. In the folded configuration,the thin wall sections 28 and thick wall sections 30 form pleats 39 orfolds in the flexible middle portion 24 of the ovenware container 20.

With reference to FIG. 1, in addition to the thin wall sections 28, toenable the folding ability and the self supporting characteristics ofthe ovenware container 20 the container includes a middle portion 24that is flexible and slightly softer than the bottom portion 22 or topportion 26. Preferably the middle portion 24 is constructed with ahardness of between 70 and 85 Shore A hardness and the bottom portion 22and top portion 26 are constructed with a hardness of greater than 85Shore A. The middle portion 24 is constructed of a flexible, resilientmaterial, such as silicone rubber, and therefore the container canwithstand many repeated folding cycles without any cracking at the thinwall sections 28. Having the top 26 and bottom 22 portions harder than85 Shore A enables the top portion 26, when pressed on the top edge 32,to maintain its rigidity and thereby allows the middle portion 24 tofold evenly and in a controlled fashion toward the bottom portion 22.The hard top 26 and bottom 22 portions further promote easier handlingof the foldable ovenware container 20, as the top 26 and bottom 22 donot buckle or flex when grasped. This is a significant advantage overprior art soft ovenware containers, which typically have thin walls anda hardness rating in the range of 40 Shore A, making them verysusceptible to buckling and leading to spillage of the contents of theprior art soft ovenware containers. Furthermore, the hard top 26 andbottom 22 portions enable the ovenware container of the presentinvention to be a stand-alone container. The ovenware container 20 ofthe present invention is therefore capable of accepting and beingcarried with any kind of food, including liquids such as soups, withoutbeing supported by an external pan or other support. Prior art softovenware containers, in contrast, must be supported by a pan or othersupport device in order to lessen the chance of spillage caused bybuckling of the sides, which is very possible with ovenware containershaving a hardness rating of about 40 Shore A. The ovenware container 20of FIG. 1, being constructed entirely of silicon rubber, can be used inboth conventional and microwave ovens as microwave radiation is notabsorbed by the silicon rubber.

In the preferred embodiment shown in FIG. 1, the ovenware container 20is preferably constructed of an elastomeric polymer such as food gradesilicone rubber. The top portion 26 and bottom portion 22 are preferablyeach formed in a separate mold by compression molding. The molds areeach filled with an uncured silicone rubber composition and are cured toobtain a Shore A hardness of greater than 85 in the resultant cured top26 and bottom 22 portions. The top 26 and bottom 22 portions are thenplaced in a third mold for forming the final ovenware container 20. Thebottom portion 22 is placed in the bottom of the mold, an uncuredsilicone rubber composition is inserted on top of the bottom portion 22,and the top portion 26 is placed in the top of the mold. The uncuredsilicone rubber composition introduced to the third mold contains ameasured quantity of hardness agent to obtain a Shore A hardness ofbetween 70 and 85 in what will become the middle portion 24 of theovenware container. The mold includes sufficient uncured silicone rubberto ensure intimate contact of the uncured silicone rubber with theentire periphery of both the bottom 22 and top 26 portions. The curingcycle preferably includes between 5 and 13 minutes of curing time atbetween 120 and 180 kg force per cm² and at a cure temperature ofbetween 140 and 200 degrees Celsius. The parameters of the curing cycleare varied according to the size of container, the grade of uncuredsilicone rubber introduced to the mold, the thickness of the container,the amounts and types of additives within the uncured silicone rubbercomposition, and various other factors. After the curing cycle, theovenware container includes a bottom portion 22 of cured silicone rubberhaving a Shore A hardness of greater than 85, a middle portion 24 ofcured silicone rubber having a Shore A hardness of between 70 and 85,and a top portion 26 having a Shore A hardness of greater than 85. Afterbeing cured, the top 26 and bottom 22 portions of the ovenware container20 are securely bonded to the middle portion to form the integralovenware container 20 and the ovenware container is oven safe to 530degrees F.

The top 26 and bottom 22 portions of the ovenware container 20 shown inFIG. 1 can also be formed from a ceramic and silicone rubber mixture.Ceramic powders can be mixed with the uncured silicone rubber to furtherraise the hardness of the top 26 and bottom 22 portions. Aluminum oxideis one example of a ceramic powder that can be added to the uncuredsilicone rubber to increase the Shore A hardness rating of the curedsilicone rubber and ceramic mixture.

A second embodiment of the ovenware container 40, shown in FIG. 5,includes a bottom portion 22 that is constructed of aluminum. A thirdembodiment of the ovenware container 50, shown in FIG. 6, has both thebottom portion 22 and top portion 26 constructed of aluminum. As thesetwo embodiments illustrate, the top 26 and bottom 22 portions of theovenware container can be constructed of other appropriate materialsthat include the desired Shore hardness of greater than 85. The topportion 26 and the bottom portion 22 therefore can be constructed ofmetal. Preferably the bottom portion 22 is a metal with a high heattransfer coefficient. A list of preferred metals for the bottom 22 andtop portions includes copper, aluminum, and steel. Alternatively, thetop 26 and bottom portions can be constructed of ceramic, temperedglass, or borosilicate glass. All of these materials can be bondedsecurely to the silicone rubber middle portion 24 with an appropriatecycle time, temperature, and pressure in the compression moldingprocedure described above. The top 26 and bottom 22 portions, whetherconstructed of metal, ceramic, or glass, are introduced to the mold asdescribed above and uncured silicone rubber composition is introduced toform the middle portion. After the pressure, temperature, and time ofthe curing cycle are applied in the compression molding operation, thecured silicone rubber middle portion 24 is integrally bonded with theseparate top 26 and bottom 22 portions.

With reference to FIG. 7, a fourth embodiment of the ovenware container60 is shown in which the top 26 and bottom 22 portions are constructedof different products to provide different desired properties at the topversus the bottom of the ovenware container. The top portion 26 isconstructed of tempered or borosilicate glass, which has good insulatingproperties. After it has been removed from the oven, a user can graspthe top portion 26 of the ovenware container 60 with less risk of heattransfer to their fingers. The bottom portion 22 of the ovenwarecontainer 60 is constructed of aluminum, which promotes good heattransfer from the oven or stovetop to the contents of the containerduring cooking.

Another possible construction for the container of the present inventionwould include a top and bottom portion constructed of ceramic ortempered or borosilicate glass and a middle portion constructed ofsilicon rubber. Ovenware containers constructed in this manner would beappropriate for use in both conventional ovens and microwave ovens.

The present invention includes a method of forming a container includingbonding together in a molding operation, including compression moldingor injection s molding, a bottom, middle, and top portion. The bottomportion and top portion are each constructed of cured silicone rubber,metal, ceramic, tempered glass, or borosilicate glass. A mold isprovided having a cavity for accepting the bottom portion, the topportion, and an uncured silicone rubber composition between the bottomand top portions. The method includes loading the mold with the bottomcontainer portion, the uncured silicone rubber composition, and the topcontainer portion. The uncured rubber composition within the mold is inintimate contact with the bottom container portion and with the topcontainer portion. Heat and pressure are applied to the mold for alength of time to cure the uncured silicone rubber composition and forma container that includes a cured middle container portion bonded to thetop and bottom container portions. The container is then removed fromthe mold and the resultant product includes a container in which the topand bottom container portions are integrally bonded to the middlecontainer portion.

As should be obvious to a person skilled in the art, several variationscan be made in the ovenware container without departing from the scopeof the invention. It would be within the scope, for example, toconstruct the ovenware container of the present invention without ahandle rather than with a handle as was shown in the several embodimentsshown herein. It would also be within the scope of the present inventionto construct ovenware containers according to the present invention withdifferent container widths, heights, and shapes. Depending on the gradesof uncured silicone rubber, and the additives to the silicone rubbercomposition, it would be within the scope of the present invention tovary the level of heat, the pressure, and the cycle time of the curingcycle during the compression molding procedure. It would also be withinthe scope of the present invention to construct the ovenware containerin an injection molding procedure.

As the invention has been described, it will be apparent to thoseskilled in the art that the same may be varied in many ways withoutdeparting from the spirit and scope of the invention. Any and all suchmodifications are intended to be included within the scope of theappended claims.

1. A container comprising: a bottom portion; a middle portion extendingfrom said bottom portion; a top portion extending from said middleportion; said bottom portion and said top portions having a firsthardness; said middle portion having a hardness lower than said firsthardness of said bottom portion and said top portion; and thin wallsections in said middle portion.
 2. The container of claim 1 whereinsaid first hardness of said bottom portion and said top portion isgreater than 85 Shore A hardness; and said hardness of said middleportion is between 70 and 85 Shore A hardness.
 3. The container of claim1 wherein said middle portion is constructed of an elastomeric polymer.4. The container of claim 3 wherein said elastomeric polymer is siliconerubber.
 5. The container of claim 1 wherein said top portion and saidbottom portion are constructed of an elastomeric polymer.
 6. Thecontainer of claim 5 wherein said elastomeric polymer is siliconerubber.
 7. The container of claim 1 wherein said top portion and saidbottom portion are constructed of metal.
 8. The container of claim 7wherein said metal is selected from the group consisting of copper,aluminum, and steel.
 9. The container of claim 1 wherein said topportion and said bottom portion are constructed of ceramic.
 10. Thecontainer of claim 1 wherein said top portion and said bottom portionare constructed of glass.
 11. The container of claim 10 wherein saidglass is selected from the group consisting of tempered glass andborosilicate glass.
 12. The container of claim 1 wherein said topportion and said bottom portion are constructed of a mixture of siliconerubber and ceramic powder.
 13. A method of forming a container includingthe steps of: providing a bottom container portion constructed of curedsilicone rubber, metal, ceramic, or borosilicate glass; providing a topcontainer portion constructed of cured silicone rubber, metal, ceramic,or borosilicate glass; providing an uncured silicone rubber composition;providing a mold having a cavity for accepting said bottom containerportion, said uncured silicone rubber composition, and said topcontainer portion; placing in order in said mold said bottom containerportion, said uncured silicone rubber composition, and said topcontainer portion, said uncured rubber composition being in contact withsaid bottom container portion and with said top container portion;curing said uncured silicone rubber in said mold in a curing cyclehaving a curing temperature, a curing pressure, and a curing cycle timeto cure said uncured silicone rubber composition and form said containerincluding a cured middle container portion bonded to said top and bottomcontainer portions; and removing said container from said mold, saidcontainer including said top and bottom container portions integrallybonded to said middle container portion.
 14. The method of claim 13wherein said cured silicone rubber of said top container portion andsaid bottom container portion includes a Shore A hardness of greaterthan
 85. 15. The method of claim 13 wherein said curing cycle includes acuring temperature of between 140 and 200 degrees Celsius; a curingpressure of between 120 and 180 kg force per cm²; and and a curing cycletime of between 5 and 13 minutes.